1. Field of the Invention
The present invention broadly relates to the field of frequency detection and, more particularly, is concerned with a circuit for monitoring a signal generated by an oscillator or the like and producing a digital display of the sign and magnitude of the deviation of the actual frequency of the signal from a preselected desired frequency when the deviation is within a predetermined range or otherwise a display of an out-of-range indication.
2. Description of the Prior Art
In many electronic systems using an oscillator or the like for generating a signal at a desired center frequency, it is oftentimes desirable to continuously monitor the frequency of the signal during operation of the system in order to be able to take immediate corrective action should out-of-tolerance deviations in the actual frequency of the oscillator signal from the desired frequency occur.
One prior art detector disclosed in U.S. Pat. No. 3,990,007 is adapted to monitor a signal and provide an indication of whether its frequency is above, below or within a given tolerance range of a predetermined frequency. However, no provision is made for determining nor digitally displaying the magnitude of deviation of the monitored signal's frequency from the predetermined frequency. Consequently, this prior art detector would be of little assistance to the operator in taking steps to fine tune the oscillator of the system when the need for corrective adjustment becomes apparent.